We recently finished our Ask the Expert discussion on Serum, Methods and Considerations for Use. This week we had many interesting questions and helpful troubleshooting methods. General serum information topics included heat inactivation, precipitates, lot qualification, types of serum, certification, and critical components. In addition more specific manufacturing questions were asked about the use of serum in mesenchymal stem cells, vaccine manufacturing and transfection.

The use of serum for the culture of cells may be a century old, but still a mainstay in cell culture applications. It is the foundation for many research protocols. There are many aspects to be considered in the selection, handing and use of serum. Ensuring consistent performance in given application can be achieved through selecting an appropriate product and maintaining the product throughout its use.

This Ask the Expert Session was Sponsored by Life Technologies and hosted by David Judd. David is the product manager of global research sera products for the Biosciences Division of ThermoFisher Scientific. David has worked for ThermoFisher for 24 years in cell culture products and applications. David has a broad array of experience in development of media for primary cells and cell lines. He has developed manufacturing processes, cell assays, biochemical analysis, cell culture processes and downstream recovery strategies. He has stepped out of the lab in order to find new ways to provide new workflow solutions for serum products for cell culture applications.

Below is a sneak peek of the discussion. For a full transcript of the discussion, please see – Ask the Expert – Serum, Methods and Considerations for Use.

What steps would you recommend for qualifying a lot of serum for vaccine manufacturing?

The Answer:

Time spent in qualification of assays for any application can pay off substantially in the long run. Designing assays for qualification of sera have to be based in the specific application. There may be more than one assay required to manage the risk for a process. Characteristics may include parameters such as cell attachment, population doubling time, viral infectivity, etc. It may be worth running through some sort of fault analysis, such as a process FMEA, to make sure all the critical points are identified. Design several assays and see which has the best assessment qualities for the specific application. Ideally it would be one short assay, but that is not always achievable. The variability in cell culture processes can make it challenging to create a single assay for multiple applications. Building up the statistical confidence in the assay is also a key function in minimizing risk. A potential pitfall is in creating assays that are very sensitive. It really needs to fit the application. If 90% of the samples pass the test and are all effective in the application – that is great. There is no value in being more discriminating when it is not necessary.

What are the most critical components in FBS that help in cell culture?

The Answer:

There are many functions that FBS supplies. Which ones are most important likely relies on the application. It provides attachment factors, growth factors, simple nutrients like amino acids and vitamins, stability factors for nutrients through binding, etc.The list is a very long one. These are the reasons it is difficult stop using it. I makes the culture of cells relatively simple and stable through so many functions in one material.There is still more to learn about its functions in cell culture.

I have been noticing precipitates in my serum. Is this harmful to my cell culture and how can I reduced precipitates in my serum?

The Answer:

Finding precipitates in serum is not uncommon. They can be composed of proteins, lipids, salts and any combination of these. It should not affect the performance of the serum at all. Precipitates can be minimized by careful thawing of the serum. Do not overexpose to heat and mix gently while thawing. Keep the number of freeze thaw cycles to a minimum.